Spark plug



A ril 22, 1924; 1,491,034

A. DE CLA IRMONT SPARK PLUG Filed SBDL 1O 1921 Patented Apr. 22, 1924.

' UNITED STATES 'PTENT', OFFlCE.

ADOLFO DE CLAIRMONT, F TOLEDO, OHIO, ASSIGNOR- TO THE CARBQ-GAS COMPANY,

or rot izoo, QHIO.

sPARK FL'UGm Application filed September 10, 1921. Serial Ho. 499,816.

To all whom it may'conce'm:

Be it known that I, ADoLro on CLAIR- MONT, citizen or" the United States, residing at Toledo, in the county of Lucas and State of Ohio, have invented certain new and useful Improvements in Spark Plugs, of which the followingis a specification. This invention relates to an improved spark plug and has as one of its principal objects toprovide a device of this character embodying an auxiliary sparking gap.

A, further object of the invention is to provide a plug wherein the auxiliary gap will be readily accessible but wherein said ap will also, nevertheless, be effectually fioused and protected.

A still further object of the invention is to provide a plug employing in conjunction with the auxiliary gap, an electrode which willserve in the capacity of a condenser.

And the invention has as a still further object to provide a plug wherein the electrode ofthe auxiliary gap will be locked against accidental displacement.

Other and incidental objects will appear hereinafter.

In the drawing: v

Figure 1 is a vertical sectional view taken medially through my improved plug,

Figure 2 is a transverse sectional view on the line 2-2 of Figure v1, looking in the direction of the arrows,

Figure 3 is a fragmentary section showing1 a slightly modified form of insulator, an 4 Figure 4 is a fragmentary section showing a slight modification.

In carrying the invention into effect, I employ a shell externally threaded at its lower end for engagement in the usual spark plug orifice of an engine cylinder and mounted in the shell is an insulator 11 having upper and lower shoulders with which are arranged to coact appropriate. gaskets 12 and 13. Asparticularly shown in Figure 2, the shell is overturned against the gasket 12 for firmly binding the insulator within the shell while the gasket 13, of course, yieldably sustains the insulator. The insulator may beconstructed of porcelain or other approved material and is formed with a tapered lower end portion 14 terminating within the skirt of the shell and a cylindrical upper end portion 15 projecting above the shell. If preferred, the insulator may, as shown in Figure 3, be provided at its lower end with a depending skirt 14 In the portion 15 of said insulator is formed a diametric opening 16 andembedded in the insulator at substantially right angles to sand opening is a diametrlcally arranged cross rod providing an electrode 17, the electrode passing centrally through the opening. Embedded in the insulator to extend I axiallythereof is an electrode 18 the upper end of which enters the opening 16, providing a spark gap 19 between said electrode and the electrode 17. The lower end of the,

electrode 18 extends below the shell 10 and fixed to said electrode is a preferably sphericalsparking terminal 20. Arranged tocooperate with the terminal 20 are ground electrodes 21 which are suitably fixed to the lower end of the shell. Preferably, a pair of the electrodes 21 is employed and these electrodes are arranged to confront the terminal 20 at opposite sides thereof, a pair of like spark gaps being formed between the terminals and said electrodes. Threaded through the upper end portion 15 of the insulator axially'thereofis an electrode 22' projecting into theopening 16 to define a spark gap 23 between said electrode and the electrode 17. The electrode 22 is, of

course, adjustable for varying the length of said gap and threaded u on the electrode to coact with the upper on of the insulator is a jam nut 24: for securing the electrode in adjusted position. Snugly but removab-ly fitting over the cylindrical upper end portion 15 of the insulator is a protecting sleeve 25 resting against the upper end of the shell. The sleeve may be formed of porcelain or other approvedmaterial and, as will be observed, said sleeve serves to close the opening 16 at its ends so that the spark gaps 19 and 23 will be effectually housed by the sleeve while the sleeve will also prevent accidental dislocation or the electrode '17.

Threaded'upon the electrode 22 to overlie the upper end edge of the sleeve is acap 26 clamping-the sleeve in position, the cap seating against the upper end of the insulator and being recessed to accommodate the nut 24:. Threaded upon the electrode to coact with said cap is a thumb nut 27 by which a circuit wire may be connected to the electrode, as will be well understood.

As will now be readily understood in view of the preceding description, when a circuit is closed through the plug, current will flow through the electrode 22 to jump across the cap 23 to the electrode 17. The current will then jump from this electrode to theelectrode 18 across the gap 19. Thus, the current will reach the sparking terminal 20, when the current will then jump to either or both of the electrodes 21 to ground. Thus, in addition to the spark gaps at the sparking terminal 20, two auxiliary gaps are provided, namely, the gaps 19 and 23 and, of course, in thus increasing the resistance to the flow of current through the plug, the effective operation of the plugrwill be enhanced; As will be perceived, the electrode 17 will serve in the capacity of a condenser, the current being dammed up in said electrode until the gap 19 is broken down. Also, the sparking terminal 20 will serve in like capacity, the current being dammed up in this terminal until either or both of the gaps to the electrodes 21 are broken down. I accordingly provide a plug which, in practical use, will prove highly eificient since the plug will fire even under extremely adverse conditions.

In Figure 4, I have illustrated a slight modification of the invention wherein the insulator, indicated at 28, is removably fitted within the shell, the shell being indicatedat 29. The parts 28 and 29 correspond, of course, to similar parts of the preferred construction and surrounding the insulator is a gasket 30 corresponding to the gasket 12. Threaded into the shell to coact with said gasket is a nut 31 bindin the insulator Within the shell and, as will %e-at once understood, this nut may be removed for freeing the insulator. Otherwise, this modification is identical with the preferred form of the invention.

Having thus described the invention, what is claimed as new is:

1. A spark plug including a shell, an insulator carried thereby and provided with an opening, coacting electrodes uponthe insulator projecting into said opening to provide an auxiliary spark gap, a third electrode upon the insulator intersecting said opening to extend between said first mentioned electrodes, and means closing said opening and locking said last mentioned electrode against displacement. 7 2A spark plugincluding a shell. an insulator carried thereby and provided with an opening, coacting electrodes upon the in sulator projecting into said opening to provide an auxiliary spark gap, at third electrode upon the insulator intersecting said opening to extend between said first mentioned electrodes, and asleeve surrounding the insulator closing said opening and looking said lastmentioned electrode against displacement. y Y

3. A spark plug including a shell, an insulator carriedthereby, coacting electrodes upon the insulator forming an auxiliary spark gap therebetween, a third electrode upon the insulator intersecting said gap, and a sleeve surrounding the insulator locking the latter electrode against displacement.

4. A spark plug including a shell, an insulator carried thereby and having its upper end portion projecting above the shell, eoacting electrodes upon the insulator forming an auxiliary gap therebetween, a third electrode upon the insulator intersecting said gap, and protecting means covering the projecting upper end portion of the insulator locking thelatter electrode against displacement.

In testimony whereofl aflix my signature.

ADOLFO DE CLAIRMONT. [Ls] 

